Merge release/delivery (IAM single sign-on) into the triage work

Brings the four release/delivery commits (IAM SSO for the admin panel,
both apps and the API; IAM env in docker-compose) onto fix/issues-triage.

Conflicts:
- customer-auth.service.ts imports: both kept.
- both apps' api/client.ts: both kept (AccountingBalance/WageQuote, and
  iamAppUrl).
- all build output (admin-panel, user-app, user-app-v2 dist, and the api
  release bundle): rebuilt from the merged source instead of picking a
  side.

Fixed while verifying:
- The IAM change calls iam.browserBootstrapUrl after every login, but
  the identity-service stand-ins in three test files lacked it. 15 tests
  failed on release/delivery itself.
- SMS relay: SMS_RELAY_PLATFORM was read but never sent, so the gateway
  never got `platform` (documented body: phone, host, text, platform).
  relayConfig() now returns it ("default" → null) and the request carries
  it. sms.service.spec now passes.

All 249 API tests pass; the three front-ends type-check and build.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/api/src/modules/auth/auth.service.spec.ts

@@ -72,7 +72,7 @@ describe('AuthService login', () => {
       service: new AuthService(
         prisma as never,
         jwt as never,
-        iam as IamService,
+        { browserBootstrapUrl: () => null, ...iam } as IamService,
         sessions as AdminSessionService,
       ),
       prisma,